Riverside County broadens attack on oak disease

DAVE DOWNEY - Staff Writer

County agricultural officials are widening their preemptive
strike against a disease that has felled tens of thousands of trees
in Northern California and poses a serious threat to western
Riverside County's majestic oaks.

The threat is also triggering a plan for visitors to scrub
hiking boots before they hit the trail.

The five-member county Board of Supervisors voted unanimously
this week to beef up a program launched in March 2004 with the goal
of preventing sudden oak death disease from hitchhiking into the
area on limbs and leaves of plants grown in other counties.

Riverside County already is spending $250,000 to attack the
growing problem. That pays for four inspectors who examine
shipments of commercially grown trees and shrubs shipped into and
out of the county, said Dustin Wiley, the county's assistant
agricultural commissioner.

The county is going to spend an additional $62,218 between now
and June to pay the salary, benefits and equipment of a lead
inspector. Upon being hired sometime this fall, that person will
direct the county's sudden oak death prevention campaign and direct
the four existing inspectors, who also have other responsibilities,
Wiley said.

"We're getting one full-time person who will concentrate
entirely on sudden oak death," he said.

There is plenty of reason to concentrate on the disease,
officials and scientists say. While arid Riverside County is hardly
as lush as the coastal forests of Northern California that have
been ravaged by sudden oak death, the area is home to dense groves
of spreading coast live oaks in the mountains of the Cleveland
National Forest and Santa Rosa Plateau.

"It's extremely important to preserve our native oaks," said
county Agricultural Commissioner John Snyder. "They're a very
special tree."

Wiley said that for years milk was the county's most lucrative
commodity, but nursery stock —— everything from trees and
ornamental plants to turf —— took over the top spot in 2003. The
nursery industry produced $211.3 million worth of products in
2004.

Wiley said inspectors are trying to prevent the disease from
coming into the area on the coattails of nursery stock grown
elsewhere by sampling arriving shipments. So far, one shipment was
found to be contaminated and the infected plants were destroyed, he
said. Infection has not been detected in any locally grown trees,
he said.

"We want to keep the disease from spreading to Riverside
County," Wiley said. "There are areas of natural lands in other
parts of the state where all the trees have died. Once the trees
are gone, it takes many years to get them back."

Since being discovered in Santa Cruz and Marin counties in 1995,
sudden oak death has laid waste to groves in 14 counties, extending
from Humboldt in the north southward to Monterey, according to the
University of California Cooperative Extension. Oozing dark cankers
break out on the trunks of infected trees.

The disease is caused by a fungus-like organism that thrives in
cool, moist conditions and is spread by plants, wind-driven rain
and humans.

Rob Hicks, park interpreter for the Santa Rosa Plateau
Ecological Reserve, said, "The most visited places tend to have the
most numbers of trees being affected."

It is believed that spores are tracked into areas by hikers.
Consequently, reserve officials plan to set up wash basins at
trailheads this fall to encourage people to scrub their boots
before heading out to see the area's native woodlands and
grasslands.

"It's not fool-proof, and it's definitely not going to be 100
percent effective," Hicks said. "But it is supposed to kill a lot
of the spores that attach themselves to the soles of the
boots."

Reserve Manager Carole Bell said UC Riverside scientists
launched in April a three-year study to look for the presence of
sudden oak death on the sprawling plateau. So far they have not
found anything to suggest the disease is there, she said.

Zach Principe, an ecologist with the Nature Conservancy in San
Diego, said that on the plateau and elsewhere in Southwest
Riverside County the greatest concern is the coast live oaks and
similar interior live oaks.

"They're the bigger, darker green trees that grow in the
canyons," Principe said.

On the other hand, the rare Engelmann oaks that live on plateau
grasslands are not believed to be at risk, he said.

The disease's spread south from Monterey may be inevitable.

"With the amount of people that go hiking in different areas and
drive vehicles in different areas, there should be no doubt that
eventually it will get to our area," Principe said. "It is just a
matter of whether, once it is here, is it going to do large-scale
damage?"